The subject matter described herein relates to manufacturing techniques and, more particularly, to systems and methods to cold work material stackups, which include metal/composite structures.
Fastener holes in metal structures may be cold worked to improve fatigue performance of the metal structure proximate the area of the fastener holes to reduce the likelihood of failure from stress cracks and the like. Such an operation commonly involves inserting a split metal sleeve and a solid mandrel into the fastener hole and drawing a mandrel through the split sleeve to introduce radial and axial stresses in the metal structure proximate the fastener holes, which strengthens the metal by plastic deformation.
Material stackups may include one or more layers of composite material, such as fiber-reinforced plastic, positioned adjacent a metal layer. In general, structures made of composite material react unfavorably to plastic deformation of the type inflicted during cold working. Thus, existing manufacturing techniques do not allow cold working of metal layers assembled into a metal/composite stack without either time-consuming disassembly of the stack or the use of part-specific tooling.